Lexapro (escitalopram) is an antidepressant belonging to a group of drugs called selective serotonin reuptake inhibitors (SSRIs). The way escitalopram works is still not fully understood. It is thought to positively affect communication between nerve cells in the central nervous system and/or restore chemical balance in the brain. Lexapro is used to treat anxiety in adults. Lexapro is also used to treat major depressive disorder in adults and adolescents who are at least 12 years old.